wiring for drag chains

**johngoodrich** · 01-08-2011

hi all. i'm looking for a good type of screened wire to use in my drag chains when they arrive. i've looked at the cy series of screened cable but some websites say it isn't reccommended for drag chains whilst others say its ok. opinions please

**Jonathan** · 01-08-2011

Chip and I have used it... his is in a drag chain. No problem so far as I know. It would be hard to tell if the shielding is breaking though which I suspect is what could cause it to fail.

**Web Goblin** · 01-08-2011

CY is ok for drag chains but does suffer from breakage over time. I have replaced loads of the stuff over the years. Give it a good stretch before you install it and make sure it is firmly secured at both ends of the drag chain so that it doesnt pull itself into the drag chain and start to coil up with the repeated movement. Also be careful
about how you unwind the cable before installation. Roll it from the drum so that it doesnt twist.

Ian

**Robin Hewitt** · 03-08-2011

Originally Posted by johngoodrich

hi all. i'm looking for a good type of screened wire to use in my drag chains

What do you want to screen?

Screened cable is capacitive and you have to be wary of ground loops.

Twisted pair is often the better option for low voltage signal connects.

**Jonathan** · 03-08-2011

Originally Posted by Robin Hewitt

What do you want to screen?

Probably stepper motors ... it generally is here.

Originally Posted by Robin Hewitt

Twisted pair is often the better option for low voltage signal connects.

I thought that twisted pair only helps with interference if used with differential signalling where complimentary signals are send down the two wires and the difference detected?

Will it stay properly twisted in the drag chain?

**Robin Hewitt** · 03-08-2011

Why would anyone want to screen a stepper motor cable?

This reeks of urban legend, a bit like choosing your motor purely on holding torque :heehee:

I'd say lots of square mm for minimum resistance and lots of strands for flex.

I use twisted pair for signal cables and you don't need fancy drivers to reap the low crosstalk benefits. Even humble RS232 at 9600 is good for 100 yards in good old Telecom twisted pair, doubt you'd get 25 with screened.

**Jonathan** · 03-08-2011

Originally Posted by Robin Hewitt

Why would anyone want to screen a stepper motor cable?

So you can listen to the radio whilst the machine's running of course!

If I don't ground the shielding on my motor cables the radio (not digital) hisses a lot etc ... with the shielding grounded it's fine. I've never been able to detect the shielding making a difference to the motors.